Since the inception of the Human Genome Project in 1990, genetic information has evolved at such a rapid pace that clinicians and researchers are desperately seeking ways to stay abreast of current knowledge. Helix: A Directory of Medical Genetics Laboratories (formerly A National Directory of DNA Diagnostic Laboratories) was founded in 1992 in response to these information needs. Helix is a central resource for identifying those laboratories performing either clinical diagnostic or research molecular testing on heritable disorders. Through Helix, a computer-based directory which lists laboratories by disease, clinicians may identify laboratories performing diagnostic testing for the genetic counseling and/or prenatal diagnosis of a family affected with or at risk for a specific inherited disorder. Helix impacts health care delivery by l) saving significant amounts of provider time searching for a suitable laboratory, which translates into a savings of health care dollars, 2) increasing the likelihood that appropriate and available diagnostic tests are utilized, thereby assuring maximum benefits of genomic information to families; and 3) providing a network to allow clinicians and laboratories to create mutually beneficial alliances to promote development of policies and procedures in the rapidly expanding field of genetics. Families with rare inherited disorders for which clinical diagnostic testing is not yet available may be linked with an appropriate research laboratory through Helix thereby enhancing patient ascertainment fbr researchers and potentially aiding in the discovery of new gene loci. While a majority of Helix users access the database for such patient-care-related purposes. we have found that the data in Helix are also utilized in quality assurance, education, public awareness, and the shaping of health policy. User feedback indicates that Helix is widely regarded as a unique and valuable resource by medical geneticists, genetic counselors and genetics laboratories. Helix received its first three years of funding through a contract with the National Center for Biotechnology Information (NCBI) in November 1992. Since becoming operational in August of 1993, Helix has grown steadily with a current listing of 263 diseases for which testing is provided by 201 laboratories. Over 2000 registered users make 30-35 inquiries per day. This application seeks continued support for the maintenance and further development of Helix, including enhancement of the quantity and quality of information contained in the directory, and improved service delivery through on-line access.